This invention is a high speed sailboat design incorporating features that improve sailing efficiency and minimize aerodynamic drag. The initial goal of this invention is to break the world sailing speed record for distance traveled over 24 hours and speed over a 500 meter course. At the time of this application, the current 24 hour distance record is 766.8 nautical miles (an average speed of 31.95 knots) set in 2006 by Orange II, a 120 foot long catamaran. The outright speed record on a 500 meter course is 48.70 knots set in 2005 by a windsurfer. For a boat, the outright speed record on a 500 meter course is 46.52 knots set in 1993 by Yellow Pages Endeavor, a one tack design with a self-supported rigid sail.
Like Orange II, this invention will likely use a catamaran design because it provides inherent lateral stability while eliminating the need for ballast below the waterline, therefore eliminating a significant source of hydrodynamic drag. Like Yellow Pages Endeavor, this invention will use a self-supported rigid sail, which provides superior aerodynamic efficiency compared to traditional flexible sails while eliminating standing rigging, therefore eliminating a significant source of aerodynamic drag. And like a windsurfer shifting his or her weight to balance the rolling moment produced on the sail, this invention will use sail-mounted ballast above the waterline to balance the rolling moment produced on the sail by the wind. But unlike a windsurfer, the human operator will not be exposed to the air and will therefore not add to the aerodynamic drag experienced by the sailboat.
In short, this invention is a catamaran sailboat design that uses a three degree-of-freedom pivot assembly to position the sail for optimum aerodynamic efficiency, which in turn positions the sail-mounted ballast to provide an anti-heeling capability.
Prior craft to which this invention can be usefully compared and contrasted are listed below. The ability to tilt the sail to windward has been previously suggested in U.S. Pat. Nos. 4,917,036; 5,509,368; and 6,058,867, but these devices are limited to tilting athwartships. The ability to pivot the sail about 2 or 3 degrees-of-freedom has been previously suggested in U.S. Pat. Nos. 4,653,417; 4,945,845; 5,060,950; 5,918,561; 6,105,524; 6,341,571; 6,779,473; and 6,789,489, but none of these devices control the sail's orientation in the same way as the present invention. The use of rigid sails and aerodynamic control surfaces has been previously suggested in U.S. Pat. Nos. 4,674,427; 6,341,571; and 6,691,632, but none of these previous inventions are similar in function to the present invention because they are all intended to fly for brief periods of time. The idea of movable ballast above the waterline has been previously suggested in U.S. Pat. Nos. 4,286,533; 5,529,007; 5,560,310; and 5,884,575, but none have ballast mounted to the sail in the same way as the present invention.
The devices in U.S. Pat. Nos. 5,918,561 and 6,341,571 have noteworthy similarities to the present invention. The sailboat in U.S. Pat. No. 5,918,561 has the ability to orient the sail for optimum efficiency about three degrees-of-freedom but does not use a single pivot assembly to control the movement of the sail. Nor does it have the capability to control movement of the sail about similar axes to the pivot assembly in the present invention. U.S. Pat. No. 6,341,571 incorporates a similar three degree-of-freedom pivot assembly with rotation about similar axes to the pivot assembly described herein, but the control mechanisms and purposes for the two pivot assemblies are different. Specifically, the pivot assembly in U.S. Pat. No. 6,341,571 is used to control the orientation of a pair of canted wing-sails whereas the pivot assembly in this invention is used to control the orientation of a single self-supported sail. Nor does the pivot assembly in U.S. Pat. No. 6,341,571 maintain the hull in a level attitude as does the pivot assembly in the present invention. Finally, the wind-powered watercraft in U.S. Pat. No. 6,341,571 is capable of flying for brief periods of time due to its inherent ability to produce a significant about of vertical lift on its pair of canted wings. The present invention does not have this flight capability because it is intended to produce much more lateral lift than the device in U.S. Pat. No. 6,341,571 and only a minimal amount of vertical lift.